var denglu = document.getElementById('dl');
var hei = document.getElementById('dl1');
var bai = document.getElementById('dl2');
denglu.onclick = function () {
    hei.style.display = "block";
    bai.style.display = "block";
}
hei.onclick = function () {
    hei.style.display = "none";
    bai.style.display = "none";
}